kai-wun Posted August 2, 2011 Share Posted August 2, 2011 Hey, Looking to go (infamous1) Stage 2 tune that'll pass emissons for a 05 Legacy GT. I understand this guy has 3 stock cats, so I'm wondering if a single cat will suffice for emissions. I'm thinking of the following: -DC Sports Turbo Up-Pipe (catless) -CNT Performance Catted Downpipe -custom single 3" exhaust with Vibrant resonator/muffler OR -DC Sports Turbo Up-Pipe (catless) -CNT Performance Catless Downpipe -custom mandrel-bent, stainless single 3" exhaust with custom 3" High Flow Cat, Vibrant resonator/muffler My concern with the second option is the location of the sensors. Is it doable, viable, recommended? I don't intend on doing upgrading the turbo or internals. Do I need intercooler or bypass valve, or would stock suffice? Hopefully this'll get me close to 240whp/280wtq. Thanks! Link to comment Share on other sites More sharing options...
Mr. Sinister Posted August 2, 2011 Share Posted August 2, 2011 A single cat is more than enough to pass the sniffer. You may or may not pass a visual though. Link to comment Share on other sites More sharing options...
kai-wun Posted August 12, 2011 Author Share Posted August 12, 2011 A single cat is more than enough to pass the sniffer. You may or may not pass a visual though. Thanks! I just found this neat diagram here: http://legacygt.com/forums/attachment.php?attachmentid=62001&d=1231172289 It shows a cat post-downpipe (in the mid-pipe?). Can I go catless up/down-pipe and keep stock midpipe (or perhaps have a exhaust shop hack into it and make it 3"?) and custom exhaust? Will this help me keep emissions-friendly? //edit: Or I can go catless up/down-pipe and go: -Custom 3" stainless mandrel-bent piping (from down-pipe) -Vibrant 3" in/out High-flow Metallic Cat (part no. 7102) -Vibrant 3" in/out Ultra Quiet Resonator (part no. 1142) -Vibrant TPV TURBO Muffler w/4" Round Angle Cut Tip (3" inlet - 23" long) - part no. 1058 or maybe -Vibrant STREETPOWER Oval Muffler w/ 4.5" x 3" Oval Angle Cut Tip (3" inlet) - part no. 1045 Link to comment Share on other sites More sharing options...
goneskiian Posted August 13, 2011 Share Posted August 13, 2011 Most aftermarket DP's replace both of the catted sections of the above diagram. If it just replaces the first cat section it's called a "shorty" DP. Link to comment Share on other sites More sharing options...
ttnio Posted August 13, 2011 Share Posted August 13, 2011 In Ca. you can pass emission sniffer test with the retention of the rear cat...this is the very last cat in your detailed drawing... Although I haven't undergone yet ... it has been done and results written... Link to comment Share on other sites More sharing options...
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